Abstract

The coast of western Louisiana is presently receiving a new influx of fine-grained sediment from the Afcchafalaya River to the east, the first such sediment pulse in recorded history. The major effect of this sediment, which accumulates as fluid mud in the nearshore and at the shoreline, is to attenuate incoming wave energy, thus providing conditions favorable for further sedimentation. Examination of color infrared photography and comparison of observations from aerial overflights and information from ground reconnaissance undertaken periodically since 1969 indicate that mudflat sedimentation is increasing and appears to be moving to the west. When muds move ashore and begin to dewater after becoming "shore attached," they gain strength rapidly and can resist subsequent fair-weather wave 3 scour if their bulk density exceeds 1.20-1.25 g/cm . An understanding of why and how these fluid muds accumulate and move subaqueously may provide us with the ability to predict areas of future erosion and accretion along the western Louisiana shoreline.